PDA

View Full Version : 2000 mustang stalling out around 4500 rpms



Steeevooo
03-23-2010, 05:51 PM
Ok so im beyond puzzled about what to do with this thing. Its a 2000 mustang gt with the 4.6 in it, we've had it on the diagnostic machine and it told us to change the number 6 coil pack so we did that and all the spark plugs while we were at it. Bought a new alternator as well and fuel filter...The problem stopped for about a day and sure enough we got on it and around the 4500 mark it hesitated terribly to the point where it caught itself back around 3600 rpms. Now if we slowly jump into the rpms it doesnt do it but if we floor it is when it bogs out. The only other thing I can think of is the fuel pump but I wanted some opinions before we go and do that nightmare job.

tonykim
03-23-2010, 06:38 PM
I recently had a similar experience on my Fox stang and it turned out to be a bad coil. I could wind to 6500 rpm at part throttle but more than about 1/3 throttle it would b bog and backfire at about 3500 rpm under load. even though you changed one coil pack you may have another issue with the electrical supply to the coils. how old is the battery and what condition are the cables?

I can also speak from experience that when fuel pumps in any of these cars go it starts with a bog under load and then worsens from there. Can you check fuel pressure off the engine while it's under load?

Steeevooo
03-24-2010, 06:54 PM
We just had it on the diagnostic machine today again and nothing came up...we changed the coil pack that was bad and its reading fine but still doing it...the battery is original and I didnt check the cables yet but ill do that tomorrow asap and ill go and pick up a fuel pressure gauge as well and wire it in

tonykim
03-25-2010, 04:35 PM
when was the last time you changed the fuel filter?

modular93fox
03-27-2010, 06:52 PM
how about a bad cat... maybe its not letting the engine exhale... i remember an instructor telling us that a cogged cat would perform "ok" on the street but on the freeway, or maybe in your case would be like maxing the motor out... maybe crawl under there and have your buddy rev it up for a min or 2... see if they are glowing red??

streetrods
03-27-2010, 07:45 PM
I have an 01 gt and had a coil on plug go bad... just to rule out the others I would swap that new with the other 7 one at a time and see if it goes away... Mine slowly got worse and worse..

Steeevooo
03-28-2010, 05:48 PM
the first thing that was changed was the fuel filter...was my first suspicion
...still did it then we tried the new coil all the way around still did it and there are no cats on it anymore they were removed...im still completely baffled...only thing left is the fuel pump and i hate doing in tanks =/

tonykim
04-01-2010, 08:26 PM
have you tried hooking up a fuel pressure gauge yet. if it isn't fuel this will keep you out of the tank. also is this 4.6 all stock on timing?

megaladon6
04-03-2010, 06:43 AM
do a graph of the cam sensor and the crank sensor and look for "holes".
also monitor your O2 sensors through the rpm range. if the system leans out that may be the fuel pump, if it goes rich, that's probably ignition